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Step 4The video and last words
Now we have 80 LEDs connected into a 5x4x4 cube. Consisting of 14 charlieplex lines.
Those of you who actually read the referenced articles in the intro will note this is a sparse charlieplex matrix. With 14 lines, I could theoretically connect 13x14=182 LEDs.....however the wiring would have been more complex.
The remaining part of the circuit was simply the charlieplex line current limiting resistors, a very simple PSU (7805 regulator) and a PIC with an IR receiver connected. When the silly season is over I'll hopefully be releasing the PIC program, but it basically sends random PWM signals down the lines, an IR remote can control the speed and distribution of the PWM patterns.
Note this isn't strictly charlieplex driving, I'm not addressing each individual LED one by one, switching lines tri-state as needed. However random PWM signals seem to work great with charlieplex grids....if you like randomly pulsing LEDs that is. Too close to Christmas to finish that part of the setup.
One thing to notice if you don't properly tristate lines when driving a charlieplex grid, is that one LED will light brightly, and several others will light up dimly. It's a little unpredictable, however for random patterns this is no problem because an element of randomness is what you want.
Coming next article will be a proper charlieplex driving scheme where individual LEDs can be lit up and some more interesting patterns made. I'm hoping to do a sort of 3D game of life unit, and perhaps re-do the grid with nicer, larger, neater sections made of pet cage mesh. I was only slightly whelmed by how it turned out with hand soldering the grid.
For now here is a pretty video (warning 9Mb).....sorry I didn't have time to youtube it.
Hopefully this brief article has shown how to make use of the charlieplexing method of driving LEDs and will put those old LED christmas string lights to good use.
Those of you who actually read the referenced articles in the intro will note this is a sparse charlieplex matrix. With 14 lines, I could theoretically connect 13x14=182 LEDs.....however the wiring would have been more complex.
The remaining part of the circuit was simply the charlieplex line current limiting resistors, a very simple PSU (7805 regulator) and a PIC with an IR receiver connected. When the silly season is over I'll hopefully be releasing the PIC program, but it basically sends random PWM signals down the lines, an IR remote can control the speed and distribution of the PWM patterns.
Note this isn't strictly charlieplex driving, I'm not addressing each individual LED one by one, switching lines tri-state as needed. However random PWM signals seem to work great with charlieplex grids....if you like randomly pulsing LEDs that is. Too close to Christmas to finish that part of the setup.
One thing to notice if you don't properly tristate lines when driving a charlieplex grid, is that one LED will light brightly, and several others will light up dimly. It's a little unpredictable, however for random patterns this is no problem because an element of randomness is what you want.
Coming next article will be a proper charlieplex driving scheme where individual LEDs can be lit up and some more interesting patterns made. I'm hoping to do a sort of 3D game of life unit, and perhaps re-do the grid with nicer, larger, neater sections made of pet cage mesh. I was only slightly whelmed by how it turned out with hand soldering the grid.
For now here is a pretty video (warning 9Mb).....sorry I didn't have time to youtube it.
Hopefully this brief article has shown how to make use of the charlieplexing method of driving LEDs and will put those old LED christmas string lights to good use.
ledcube.MOV9 MB| « Previous Step | Download PDFView All Steps | Next Step » |
I'm not sure how much it will complicate the layout.
I saw this article and you're right, you can drive multiple LEDs at a time.
Funnily enough we've been through this issue several months ago. Check out my other instructable:
http://www.instructables.com/id/Charlieplexing-LEDs--The-theory/
where there was a lively discussion and some results on multi-LED charlieplexing in the comment section.
Phil